shared: add process-util.[ch]

1 files changed, 538 insertions, 0 deletions

diff --git a/src/shared/process-util.c b/src/shared/process-util.c
new file mode 100644
index 0000000000..92a69f50e7
--- /dev/null
+++ b/src/shared/process-util.c
@@ -0,0 +1,538 @@
+/***
+  This file is part of systemd.
+
+  Copyright 2010 Lennart Poettering
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <stdbool.h>
+#include <sys/types.h>
+#include <string.h>
+#include <stdio.h>
+#include <assert.h>
+#include <errno.h>
+#include <unistd.h>
+#include <sys/wait.h>
+#include <signal.h>
+#include <ctype.h>
+
+#include "process-util.h"
+#include "fileio.h"
+#include "util.h"
+#include "log.h"
+
+int get_process_state(pid_t pid) {
+        const char *p;
+        char state;
+        int r;
+        _cleanup_free_ char *line = NULL;
+
+        assert(pid >= 0);
+
+        p = procfs_file_alloca(pid, "stat");
+        r = read_one_line_file(p, &line);
+        if (r < 0)
+                return r;
+
+        p = strrchr(line, ')');
+        if (!p)
+                return -EIO;
+
+        p++;
+
+        if (sscanf(p, " %c", &state) != 1)
+                return -EIO;
+
+        return (unsigned char) state;
+}
+
+int get_process_comm(pid_t pid, char **name) {
+        const char *p;
+        int r;
+
+        assert(name);
+        assert(pid >= 0);
+
+        p = procfs_file_alloca(pid, "comm");
+
+        r = read_one_line_file(p, name);
+        if (r == -ENOENT)
+                return -ESRCH;
+
+        return r;
+}
+
+int get_process_cmdline(pid_t pid, size_t max_length, bool comm_fallback, char **line) {
+        _cleanup_fclose_ FILE *f = NULL;
+        char *r = NULL, *k;
+        const char *p;
+        int c;
+
+        assert(line);
+        assert(pid >= 0);
+
+        p = procfs_file_alloca(pid, "cmdline");
+
+        f = fopen(p, "re");
+        if (!f)
+                return -errno;
+
+        if (max_length == 0) {
+                size_t len = 0, allocated = 0;
+
+                while ((c = getc(f)) != EOF) {
+
+                        if (!GREEDY_REALLOC(r, allocated, len+2)) {
+                                free(r);
+                                return -ENOMEM;
+                        }
+
+                        r[len++] = isprint(c) ? c : ' ';
+                }
+
+                if (len > 0)
+                        r[len-1] = 0;
+
+        } else {
+                bool space = false;
+                size_t left;
+
+                r = new(char, max_length);
+                if (!r)
+                        return -ENOMEM;
+
+                k = r;
+                left = max_length;
+                while ((c = getc(f)) != EOF) {
+
+                        if (isprint(c)) {
+                                if (space) {
+                                        if (left <= 4)
+                                                break;
+
+                                        *(k++) = ' ';
+                                        left--;
+                                        space = false;
+                                }
+
+                                if (left <= 4)
+                                        break;
+
+                                *(k++) = (char) c;
+                                left--;
+                        }  else
+                                space = true;
+                }
+
+                if (left <= 4) {
+                        size_t n = MIN(left-1, 3U);
+                        memcpy(k, "...", n);
+                        k[n] = 0;
+                } else
+                        *k = 0;
+        }
+
+        /* Kernel threads have no argv[] */
+        if (isempty(r)) {
+                _cleanup_free_ char *t = NULL;
+                int h;
+
+                free(r);
+
+                if (!comm_fallback)
+                        return -ENOENT;
+
+                h = get_process_comm(pid, &t);
+                if (h < 0)
+                        return h;
+
+                r = strjoin("[", t, "]", NULL);
+                if (!r)
+                        return -ENOMEM;
+        }
+
+        *line = r;
+        return 0;
+}
+
+int is_kernel_thread(pid_t pid) {
+        const char *p;
+        size_t count;
+        char c;
+        bool eof;
+        FILE *f;
+
+        if (pid == 0)
+                return 0;
+
+        assert(pid > 0);
+
+        p = procfs_file_alloca(pid, "cmdline");
+        f = fopen(p, "re");
+        if (!f)
+                return -errno;
+
+        count = fread(&c, 1, 1, f);
+        eof = feof(f);
+        fclose(f);
+
+        /* Kernel threads have an empty cmdline */
+
+        if (count <= 0)
+                return eof ? 1 : -errno;
+
+        return 0;
+}
+
+int get_process_capeff(pid_t pid, char **capeff) {
+        const char *p;
+
+        assert(capeff);
+        assert(pid >= 0);
+
+        p = procfs_file_alloca(pid, "status");
+
+        return get_status_field(p, "\nCapEff:", capeff);
+}
+
+static int get_process_link_contents(const char *proc_file, char **name) {
+        int r;
+
+        assert(proc_file);
+        assert(name);
+
+        r = readlink_malloc(proc_file, name);
+        if (r < 0)
+                return r == -ENOENT ? -ESRCH : r;
+
+        return 0;
+}
+
+int get_process_exe(pid_t pid, char **name) {
+        const char *p;
+        char *d;
+        int r;
+
+        assert(pid >= 0);
+
+        p = procfs_file_alloca(pid, "exe");
+        r = get_process_link_contents(p, name);
+        if (r < 0)
+                return r;
+
+        d = endswith(*name, " (deleted)");
+        if (d)
+                *d = '\0';
+
+        return 0;
+}
+
+static int get_process_id(pid_t pid, const char *field, uid_t *uid) {
+        _cleanup_fclose_ FILE *f = NULL;
+        char line[LINE_MAX];
+        const char *p;
+
+        assert(field);
+        assert(uid);
+
+        if (pid == 0)
+                return getuid();
+
+        p = procfs_file_alloca(pid, "status");
+        f = fopen(p, "re");
+        if (!f)
+                return -errno;
+
+        FOREACH_LINE(line, f, return -errno) {
+                char *l;
+
+                l = strstrip(line);
+
+                if (startswith(l, field)) {
+                        l += strlen(field);
+                        l += strspn(l, WHITESPACE);
+
+                        l[strcspn(l, WHITESPACE)] = 0;
+
+                        return parse_uid(l, uid);
+                }
+        }
+
+        return -EIO;
+}
+
+int get_process_uid(pid_t pid, uid_t *uid) {
+        return get_process_id(pid, "Uid:", uid);
+}
+
+int get_process_gid(pid_t pid, gid_t *gid) {
+        assert_cc(sizeof(uid_t) == sizeof(gid_t));
+        return get_process_id(pid, "Gid:", gid);
+}
+
+int get_process_cwd(pid_t pid, char **cwd) {
+        const char *p;
+
+        assert(pid >= 0);
+
+        p = procfs_file_alloca(pid, "cwd");
+
+        return get_process_link_contents(p, cwd);
+}
+
+int get_process_root(pid_t pid, char **root) {
+        const char *p;
+
+        assert(pid >= 0);
+
+        p = procfs_file_alloca(pid, "root");
+
+        return get_process_link_contents(p, root);
+}
+
+int get_process_environ(pid_t pid, char **env) {
+        _cleanup_fclose_ FILE *f = NULL;
+        _cleanup_free_ char *outcome = NULL;
+        int c;
+        const char *p;
+        size_t allocated = 0, sz = 0;
+
+        assert(pid >= 0);
+        assert(env);
+
+        p = procfs_file_alloca(pid, "environ");
+
+        f = fopen(p, "re");
+        if (!f)
+                return -errno;
+
+        while ((c = fgetc(f)) != EOF) {
+                if (!GREEDY_REALLOC(outcome, allocated, sz + 5))
+                        return -ENOMEM;
+
+                if (c == '\0')
+                        outcome[sz++] = '\n';
+                else
+                        sz += cescape_char(c, outcome + sz);
+        }
+
+        outcome[sz] = '\0';
+        *env = outcome;
+        outcome = NULL;
+
+        return 0;
+}
+
+int get_parent_of_pid(pid_t pid, pid_t *_ppid) {
+        int r;
+        _cleanup_free_ char *line = NULL;
+        long unsigned ppid;
+        const char *p;
+
+        assert(pid >= 0);
+        assert(_ppid);
+
+        if (pid == 0) {
+                *_ppid = getppid();
+                return 0;
+        }
+
+        p = procfs_file_alloca(pid, "stat");
+        r = read_one_line_file(p, &line);
+        if (r < 0)
+                return r;
+
+        /* Let's skip the pid and comm fields. The latter is enclosed
+         * in () but does not escape any () in its value, so let's
+         * skip over it manually */
+
+        p = strrchr(line, ')');
+        if (!p)
+                return -EIO;
+
+        p++;
+
+        if (sscanf(p, " "
+                   "%*c "  /* state */
+                   "%lu ", /* ppid */
+                   &ppid) != 1)
+                return -EIO;
+
+        if ((long unsigned) (pid_t) ppid != ppid)
+                return -ERANGE;
+
+        *_ppid = (pid_t) ppid;
+
+        return 0;
+}
+
+int wait_for_terminate(pid_t pid, siginfo_t *status) {
+        siginfo_t dummy;
+
+        assert(pid >= 1);
+
+        if (!status)
+                status = &dummy;
+
+        for (;;) {
+                zero(*status);
+
+                if (waitid(P_PID, pid, status, WEXITED) < 0) {
+
+                        if (errno == EINTR)
+                                continue;
+
+                        return -errno;
+                }
+
+                return 0;
+        }
+}
+
+/*
+ * Return values:
+ * < 0 : wait_for_terminate() failed to get the state of the
+ *       process, the process was terminated by a signal, or
+ *       failed for an unknown reason.
+ * >=0 : The process terminated normally, and its exit code is
+ *       returned.
+ *
+ * That is, success is indicated by a return value of zero, and an
+ * error is indicated by a non-zero value.
+ *
+ * A warning is emitted if the process terminates abnormally,
+ * and also if it returns non-zero unless check_exit_code is true.
+ */
+int wait_for_terminate_and_warn(const char *name, pid_t pid, bool check_exit_code) {
+        int r;
+        siginfo_t status;
+
+        assert(name);
+        assert(pid > 1);
+
+        r = wait_for_terminate(pid, &status);
+        if (r < 0)
+                return log_warning_errno(r, "Failed to wait for %s: %m", name);
+
+        if (status.si_code == CLD_EXITED) {
+                if (status.si_status != 0)
+                        log_full(check_exit_code ? LOG_WARNING : LOG_DEBUG,
+                                 "%s failed with error code %i.", name, status.si_status);
+                else
+                        log_debug("%s succeeded.", name);
+
+                return status.si_status;
+        } else if (status.si_code == CLD_KILLED ||
+                   status.si_code == CLD_DUMPED) {
+
+                log_warning("%s terminated by signal %s.", name, signal_to_string(status.si_status));
+                return -EPROTO;
+        }
+
+        log_warning("%s failed due to unknown reason.", name);
+        return -EPROTO;
+}
+
+int kill_and_sigcont(pid_t pid, int sig) {
+        int r;
+
+        r = kill(pid, sig) < 0 ? -errno : 0;
+
+        if (r >= 0)
+                kill(pid, SIGCONT);
+
+        return r;
+}
+
+int getenv_for_pid(pid_t pid, const char *field, char **_value) {
+        _cleanup_fclose_ FILE *f = NULL;
+        char *value = NULL;
+        int r;
+        bool done = false;
+        size_t l;
+        const char *path;
+
+        assert(pid >= 0);
+        assert(field);
+        assert(_value);
+
+        path = procfs_file_alloca(pid, "environ");
+
+        f = fopen(path, "re");
+        if (!f)
+                return -errno;
+
+        l = strlen(field);
+        r = 0;
+
+        do {
+                char line[LINE_MAX];
+                unsigned i;
+
+                for (i = 0; i < sizeof(line)-1; i++) {
+                        int c;
+
+                        c = getc(f);
+                        if (_unlikely_(c == EOF)) {
+                                done = true;
+                                break;
+                        } else if (c == 0)
+                                break;
+
+                        line[i] = c;
+                }
+                line[i] = 0;
+
+                if (memcmp(line, field, l) == 0 && line[l] == '=') {
+                        value = strdup(line + l + 1);
+                        if (!value)
+                                return -ENOMEM;
+
+                        r = 1;
+                        break;
+                }
+
+        } while (!done);
+
+        *_value = value;
+        return r;
+}
+
+bool pid_is_unwaited(pid_t pid) {
+        /* Checks whether a PID is still valid at all, including a zombie */
+
+        if (pid <= 0)
+                return false;
+
+        if (kill(pid, 0) >= 0)
+                return true;
+
+        return errno != ESRCH;
+}
+
+bool pid_is_alive(pid_t pid) {
+        int r;
+
+        /* Checks whether a PID is still valid and not a zombie */
+
+        if (pid <= 0)
+                return false;
+
+        r = get_process_state(pid);
+        if (r == -ENOENT || r == 'Z')
+                return false;
+
+        return true;
+}